I just got some feedback from Olivier Herbert who is the CTO of Fairphone. He is investigating the matter, but wanted to share this with you:
It’s important to note that the seal is formed by the combination of both the gasket on the display frame (which is flush/slightly recessed) and the light pipe on the top module (which is protruding). The other seals are formed only by one element, hence the need to have it protruding.
I am just adding the same problem. I did clean my sensor, but it didn’t help… I know use the workaround but changing the power button but I’m also quiet disappointed in this functioning.
Annick
@Douwe: Thank you for your fast acting in this issue.
I dind’t noticed the counterpart of the seal and its a technical explanation for me.
With my curiosity i opened my FP again and had a look on this counterpart.
In my Phone the seal has an inclination, as you hopefully can see on this pictures:
Angle is flat from the bottom
I don’t want to split hairs (caution: german phrase). I hope this helps Olivier by investigating.
p.s. I would like to make those photos with my phone 
Ok, i have the same problem. The on/off button trick works when you make a regular phone call. When you call with Whatsapp, this does not work. And if nobody answers your call, you have to get the battery out (annoying). The proximity sensor does not register anything, so i wanted to open up the phone. Unfortunately i cannot slide the screen of the body. On the youtube video it seems very easy, but me and my colleagues did not work this one out. HELP
There are some tips and tricks here:
If you press and hold the power button for 15 to 20 seconds, the phone will reboot.
This should spare the tedious process of removing the battery.
Solution? In my terminal works!
I enter the phone number and pulse often any symbol (speaker, dialing fools …), the screen goes black but then activated and operating normally.
I do not speak English and I translated with google, sorry
It would seem like a logical choice to let the power button turn the screen on even if the proximity sensor thinks it is covered. At the moment the phone is an unresponsive brick when this error occurs. If the power button could turn the screen we would have a reasonable workaround for when this issue occurs.
the issue of the proximity sensor is still not solved. I have issued a repair at Fairphone, because cleaning does not work. But up till now, no reply or a repair process in effect.
Hi there
Just wanted to report that I have the same problem. Screen stays black when I move the phone away from my ear. Can’t end the call. Sometimes the screen lights up again after 10-20 seconds, sometimes it doesn’t. Then a reboot is necessary. I still have to test wether cleaning the sensor helped.
A “real” solution would be very welcome!
Erm, cleaning the sensor is the only real solution if dirt is the cause of the issue. If it doesn’t make a difference for you than that’s another story.
Sorry but cleaning the sensor maybe every week is no real solution. And I hope it is not the only solution in the future. A real solution is a solution which works continuous after execute some steps for solving the problem.
Hello,
I have been experiencing this problem since receiving my phone in February and am glad to find that there is a discussion on the go about the unresponsive screen when trying to end a call or indeed use automated hotlines. I look forward to us getting a convincing and lasting solution to this seriously user unfriendly problem.
Regularly I have to wait for the other person to hang up or remove the back of the phone, which is not a really ideal solution because taking the cover off and especially putting it back on again is extremely fiddly. Another reason why the suggestion of cleaning the proximity sensor on a recuring basis is a lame solution for the longterm.
Best regrads
Maria
Hello everyone,
Like many of you I’ve been having a similar problem. I have cleaned the sensor and screen (inside and out), enabled “power button hangs up phone”, tried the new update and so on. I have even tried multiple different ways of holding the phone.
When I tried running the Sensor Readout app, I wasn’t getting any output whatsoever from the proximity/“distance” sensor. I cleaned before and after trying this test multiple times, but was still getting no response. Does this sound like a hardware error? Have I missed anything?
Thank you.
To me it actually sounds like a hardware issue. If cleaning doesn’t help and a test so shows nothing, then the sensor might be faulty.
Hi,
i had this problem before the update, somewhere above i already mentioned it. But after the update my screen doesn’t react at all after calling as long as the other party doesn’t hang up. I clean my screen - the part where the proxymeter is, but i have to pull out my battery everytime.
Also weird to see how many people don’t hang up after calling…
Edit: as of FP2’s Software Version 1.2.8 possible:
@carloskok, an IMHO easier way to reboot your phone instead of removing the battery is to press and hold the power button (about 15 to 20 seconds) until the phone reboots.
Hi Amers,
with the previous OS that wasn’t prossible. Removing the battery wa stheonly option.
Still, hanging up would be the most easiest way 
